// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/**
 * rpivid-mem.c - character device access to the RPiVid decoder registers
 *
 * Based on bcm2835-gpiomem.c. Provides IO memory access to the decoder
 * register blocks such that ffmpeg plugins can access the hardware.
 *
 * Jonathan Bell <jonathan@raspberrypi.org>
 * Copyright (c) 2019, Raspberry Pi (Trading) Ltd.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the above-listed copyright holders may not be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * ALTERNATIVELY, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2, as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/cdev.h>
#include <linux/pagemap.h>
#include <linux/io.h>

#define DRIVER_NAME "rpivid-mem"
#define DEVICE_MINOR 0

struct rpivid_mem_priv {
	dev_t devid;
	struct class *class;
	struct cdev rpivid_mem_cdev;
	unsigned long regs_phys;
	unsigned long mem_window_len;
	struct device *dev;
	const char *name;
};

static int rpivid_mem_open(struct inode *inode, struct file *file)
{
	int dev = iminor(inode);
	int ret = 0;
	struct rpivid_mem_priv *priv;

	if (dev != DEVICE_MINOR && dev != DEVICE_MINOR + 1)
		ret = -ENXIO;

	priv = container_of(inode->i_cdev, struct rpivid_mem_priv,
				rpivid_mem_cdev);
	if (!priv)
		return -EINVAL;
	file->private_data = priv;
	return ret;
}

static int rpivid_mem_release(struct inode *inode, struct file *file)
{
	int dev = iminor(inode);
	int ret = 0;

	if (dev != DEVICE_MINOR && dev != DEVICE_MINOR + 1)
		ret = -ENXIO;

	return ret;
}

static const struct vm_operations_struct rpivid_mem_vm_ops = {
#ifdef CONFIG_HAVE_IOREMAP_PROT
	.access = generic_access_phys
#endif
};

static int rpivid_mem_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct rpivid_mem_priv *priv;
	unsigned long pages;
	unsigned long len;

	priv = file->private_data;
	pages = priv->regs_phys >> PAGE_SHIFT;
	/*
	 * The address decode is far larger than the actual number of registers.
	 * Just map the whole lot in.
	 */
	len = min(vma->vm_end - vma->vm_start, priv->mem_window_len);
	vma->vm_page_prot = phys_mem_access_prot(file, pages, len,
						 vma->vm_page_prot);
	vma->vm_ops = &rpivid_mem_vm_ops;
	if (remap_pfn_range(vma, vma->vm_start,
			    pages, len,
			    vma->vm_page_prot)) {
		return -EAGAIN;
	}
	return 0;
}

static const struct file_operations
rpivid_mem_fops = {
	.owner = THIS_MODULE,
	.open = rpivid_mem_open,
	.release = rpivid_mem_release,
	.mmap = rpivid_mem_mmap,
};

static const struct of_device_id rpivid_mem_of_match[];
static int rpivid_mem_probe(struct platform_device *pdev)
{
	int err;
	const struct of_device_id *id;
	struct device *dev = &pdev->dev;
	struct resource *ioresource;
	struct rpivid_mem_priv *priv;

	/* Allocate buffers and instance data */

	priv = kzalloc(sizeof(struct rpivid_mem_priv), GFP_KERNEL);

	if (!priv) {
		err = -ENOMEM;
		goto failed_inst_alloc;
	}
	platform_set_drvdata(pdev, priv);

	priv->dev = dev;
	id = of_match_device(rpivid_mem_of_match, dev);
	if (!id)
		return -EINVAL;
	priv->name = id->data;

	ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (ioresource) {
		priv->regs_phys = ioresource->start;
		priv->mem_window_len = (ioresource->end + 1) - ioresource->start;
	} else {
		dev_err(priv->dev, "failed to get IO resource");
		err = -ENOENT;
		goto failed_get_resource;
	}

	/* Create character device entries */

	err = alloc_chrdev_region(&priv->devid,
				  DEVICE_MINOR, 2, priv->name);
	if (err != 0) {
		dev_err(priv->dev, "unable to allocate device number");
		goto failed_alloc_chrdev;
	}
	cdev_init(&priv->rpivid_mem_cdev, &rpivid_mem_fops);
	priv->rpivid_mem_cdev.owner = THIS_MODULE;
	err = cdev_add(&priv->rpivid_mem_cdev, priv->devid, 2);
	if (err != 0) {
		dev_err(priv->dev, "unable to register device");
		goto failed_cdev_add;
	}

	/* Create sysfs entries */

	priv->class = class_create(THIS_MODULE, priv->name);
	if (IS_ERR(priv->class)) {
		err = PTR_ERR(priv->class);
		goto failed_class_create;
	}

	dev = device_create(priv->class, NULL, priv->devid, NULL, priv->name);
	if (IS_ERR(dev)) {
		err = PTR_ERR(dev);
		goto failed_device_create;
	}

	dev_info(priv->dev, "%s initialised: Registers at 0x%08lx length 0x%08lx",
		priv->name, priv->regs_phys, priv->mem_window_len);

	return 0;

failed_device_create:
	class_destroy(priv->class);
failed_class_create:
	cdev_del(&priv->rpivid_mem_cdev);
failed_cdev_add:
	unregister_chrdev_region(priv->devid, 1);
failed_alloc_chrdev:
failed_get_resource:
	kfree(priv);
failed_inst_alloc:
	dev_err(&pdev->dev, "could not load rpivid_mem");
	return err;
}

static int rpivid_mem_remove(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct rpivid_mem_priv *priv = platform_get_drvdata(pdev);

	device_destroy(priv->class, priv->devid);
	class_destroy(priv->class);
	cdev_del(&priv->rpivid_mem_cdev);
	unregister_chrdev_region(priv->devid, 1);
	kfree(priv);

	dev_info(dev, "%s driver removed - OK", priv->name);
	return 0;
}

static const struct of_device_id rpivid_mem_of_match[] = {
	{
		.compatible = "raspberrypi,rpivid-hevc-decoder",
		.data = "rpivid-hevcmem",
	},
	{
		.compatible = "raspberrypi,rpivid-h264-decoder",
		.data = "rpivid-h264mem",
	},
	{
		.compatible = "raspberrypi,rpivid-vp9-decoder",
		.data = "rpivid-vp9mem",
	},
	/* The "intc" is included as this block of hardware contains the
	 * "frame done" status flags.
	 */
	{
		.compatible = "raspberrypi,rpivid-local-intc",
		.data = "rpivid-intcmem",
	},
	{ /* sentinel */ },
};

MODULE_DEVICE_TABLE(of, rpivid_mem_of_match);

static struct platform_driver rpivid_mem_driver = {
	.probe = rpivid_mem_probe,
	.remove = rpivid_mem_remove,
	.driver = {
		   .name = DRIVER_NAME,
		   .owner = THIS_MODULE,
		   .of_match_table = rpivid_mem_of_match,
		   },
};

module_platform_driver(rpivid_mem_driver);

MODULE_ALIAS("platform:rpivid-mem");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver for accessing RPiVid decoder registers from userspace");
MODULE_AUTHOR("Jonathan Bell <jonathan@raspberrypi.org>");
